In the art of working metal, it is often necessary to cut off plates which are of considerable thickness and considerable width. This is normally accomplished by providing a fixed blade over which the plate to be cut is inserted, and providing a movable blade which normally moves downwardly in a vertical direction against the plate to be sheared, shearing the plates between the fixed blade and the vertical and movable blade.
Numerous devices have been used for this purpose. For example, U.S. Pat. No. 3,678,792 issued July 25, 1972 to Frank Dvorak discloses a frame having opposite end portions which are fixed to a supporting base which includes end members which extend upwardly to support a vertically slidable plate having a movable shearing edge along its lower edge. A fixed shearing blade is mounted upon the base. The movable plate includes a series of ramps which are spaced and similarly inclined. By forcing rollers against the ramp, and moving the rollers in unison up the ramp, the movable plate is forced downwardly to shear off the plate inserted between the shearing blades.
Numerous other forms of plate shears have been produced, one of the important differences being in the particular means of raising and lowering the movable shearing plate relative to the frame.